Using waves

P-waves vibrate vertically and can travel through solids and liquids. They travel faster that S-waves, and are a longitudinal wavelength.

S-waves are secondary waves. they are transverse waves and oscilate 90 degrees of the direction of travel and vibrate horizontally

the Earth is made up of four main layers. These are the crust, the mantle, the outercore and the innercore.

We know that P-waves can travel through both solids and liquids. When they travel through the Earth, they refract due to the different densitys and the different states. However, S-waves cannot travel through liquids, and therefore can't go through the outercore. From this evidence, we can conclude that the earth has different structured layers.

refraction is when a wave changes direction due toa difference of density's within materials.

we can pin-point the epicentre by drawing circles from different points on a map with the distance an earthquake is from the epicentre. where the circled overlap. the epicentre is located.

The lag time is the time delay between P-waves and S-waves. That, is then used to find the epicentre of the earthquake by using equations such as Speed = Distance / Time

Total internal reflection is when the wave is reflected at a point greater than the critical angle.